Elongate sheet members such as paperboards, corrugated cardboards, polyethylene sheets, aluminum foil, and the like are frequently printed, punched, or vacuum-formed in succession. One common form of apparatus for sequentially cutting or shaping elongate sheet materials comprises feed means including a drive roller and an idler roller rotatable in contact with the drive roller, and a processing machine such as a punch and die, the rollers sandwiching a continuous sheet therebetween to feed the continuous sheet from a roll to the processing machine.
Frequently, it is required that the speed of travel of the sheet material be controlled so as to be held in timed relation with the operation of the processing machine. For example, the processing machine may stamp out the sheet sequentially in conformity with patterns printed on the sheet at spaced locations therealong. Another example is a multicolor rotary printing press which prints further patterns successively in precise registry with existing patterns on the elongate sheet. One known technique for changing the speed of travel of the sheet is to provide a speed change gear in a drive mechanism for varying the speed of rotation of the drive roller. This prior art approach is however disadvantageous in that the drive mechanism is of complicated construction and is expensive accordingly. Furthermore, the speed of travel of continuous sheet cannot be changed rapidly and fine adjustment of the speed is difficult to achieve.